工厂方法模式在软件系统演化中的应用

Posted 2020-12-07 windpoplar

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一、第一阶段

1、需求

网站报500类错误时，管理员和开发人员并不能实时知道，等查看日志时或用户打电话过来返回问题时，有可能已经造成了极大的不良影响。所以需要开发一个实时通知功能，将网站的报错信息通过 Email 发送给管理员。

2、实现

写一个异常处理器，配置到系统中进行监听，渲染时走 Email 类发出去。具体代码如下。

package com.taoxi.designpattern.factorymethod.v1;

import java.util.ArrayList;
import java.util.List;

//Email类
public class Email {

    private String hostName;
    private int port;
    private String userName;
    private String password;

    private String from;
    private List<String> toAddress = new ArrayList<>();
    private String subject;
    private String message;

    //发送
    public void send(){
        System.out.println("send email!");
    }

    public String getHostName() {
        return hostName;
    }

    public void setHostName(String hostName) {
        this.hostName = hostName;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public List<String> getToAddress() {
        return toAddress;
    }

    public void setToAddress(List<String> toAddress) {
        this.toAddress = toAddress;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

View Code

package com.taoxi.designpattern.factorymethod.v1;

import java.util.ArrayList;
import java.util.List;

//错误异常处理类
public class ErrorHandler {
    //渲染异常和错误
    public void renderException() {
        String hostName = "SMTP.163.com";
        int port = 586;
        String userName = "taoxi@163.com";
        String password = "******";//授权码
        String from = "taoxi@163.com";
        List<String> toAddress = new ArrayList<String>();
        toAddress.add("tx@jd.com");
        toAddress.add("lj@jd.com");
        String subject = "报错了！";
        String message = "具体的报错内容";

        Email email = new Email();
        email.setHostName(hostName);
        email.setPort(port);
        email.setUserName(userName);
        email.setPassword(password);
        email.setFrom(from);
        email.getToAddress().addAll(toAddress);
        email.setSubject(subject);
        email.setMessage(message);

        email.send();

    }
}

View Code

3、问题

ErrorHandler 作为客户端（调用方），想发送邮件出去，却参与了邮件发送对象的初始化工作，不符合单一职责原则。

二、第二阶段

1、需求

需要让客服跟进一下异常订单的情况，有人退订单了或下单了长时间没有付款的客户，邮件通知到客服。

2、实现

再写一个订单监听器，配置到系统中进行监听，需要的时候走 EMail 类发出去。

package com.taoxi.designpattern.factorymethod.v2;

import java.util.ArrayList;
import java.util.List;

//订单监听器
public class OrderHandler {

    //通知处理
    public void notifyHandler() {
        String hostName = "SMTP.163.com";
        int port = 586;
        String userName = "taoxi@163.com";
        String password = "******";//授权码

        String from = "taoxi@163.com";
        List<String> toAddress = new ArrayList<String>();
        toAddress.add("tx@jd.com");
        toAddress.add("lj@jd.com");
        String subject = "订单异常！";
        String message = "具体的异常内容";

        Email email = new Email();

        email.setHostName(hostName);
        email.setPort(port);
        email.setUserName(userName);
        email.setPassword(password);

        email.setFrom(from);
        email.getToAddress().addAll(toAddress);
        email.setSubject(subject);
        email.setMessage(message);

        email.send();

    }
}

View Code

3、问题

可复用性太差了，更换个邮件配置还得改多处，需要优化一下了。

4、改进

把Email封装到一起。

package com.taoxi.designpattern.factorymethod.v2_1;

import java.util.ArrayList;
import java.util.List;

//Email类
public class Email {

    private String hostName;
    private int port;
    private String userName;
    private String password;

    private String from;
    private List<String> toAddress = new ArrayList<>();
    private String subject;
    private String message;

    //获取对象
    public static Email getInstance() {
        String hostName = "SMTP.163.com";
        int port = 586;
        String userName = "taoxi@163.com";
        String password = "******";//授权码

        String from = "taoxi@163.com";
        List<String> toAddress = new ArrayList<String>();
        toAddress.add("tx@jd.com");
        toAddress.add("lj@jd.com");

        Email email = new Email();

        email.setHostName(hostName);
        email.setPort(port);
        email.setUserName(userName);
        email.setPassword(password);

        email.setFrom(from);
        email.getToAddress().addAll(toAddress);

        return email;
    }

    //设置消息体
    public void initMessage(String subject, String message) {
        this.subject = subject;
        this.message = message;
    }

    //发送消息
    public void send(){
        System.out.println("send email!");
    }

    public String getHostName() {
        return hostName;
    }

    public void setHostName(String hostName) {
        this.hostName = hostName;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public List<String> getToAddress() {
        return toAddress;
    }

    public void setToAddress(List<String> toAddress) {
        this.toAddress = toAddress;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

View Code

package com.taoxi.designpattern.factorymethod.v2_1;

//错误异常处理
public class ErrorHandler {
    //渲染异常和错误
    public void renderException() {

        String subject = "报错了！";
        String message = "具体的报错内容";

        Email email = Email.getInstance();

        email.initMessage(subject, message);

        email.send();

    }
}

View Code

package com.taoxi.designpattern.factorymethod.v2_1;

//订单监听器
public class OrderHandler {
    //监听处理
    public void notifyHandler() {

        String subject = "订单异常！";
        String message = "具体的异常内容";

        Email email = Email.getInstance();

        email.initMessage(subject, message);

        email.send();

    }
}

View Code

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